Electronic device and operating method thereof

ABSTRACT

The present invention relates to an electronic device and a method of operating the electronic device. There are provided an electronic device and a method of operating the electronic device that may more effectively resolve handover request collisions by using a specific field value included in a handover request message.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/522,314, filed on Jul. 13, 2012, which is the National Stage filingunder 35 U.S.C. 371 of International Application No. PCT/KR2010/008530,filed on Nov. 30, 2010, and also claims the benefit of U.S. ProvisionalApplication Ser. No. 61/295,157, filed on Jan. 14, 2010, the contents ofwhich are all incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to an NFC electronic device that may forman NFC link and a method of operating the NFC electronic device. Morespecifically, the present invention relates to a hand over method ofswitching an NFC link formed between NFC electronic devices to analternative communication link.

BACKGROUND ART

NFC (Near Field Communication, hereinafter “NFC”) is a very short-rangecontactless data transfer technology associated with RFID (radiofrequency identification) and may be used for communication with deviceswithin a distance of 10 cm or less (preferably, 4 cm or less).

NFC employs a center frequency of 13.56 MHz and may provide atransmission rate of 106, 212, 424 kbps. NFC may be compatible withvarious contactless communication protocols, such as, for example,protocols defined in ISO 14443 type A, B, and F and ISO 18092.

NFC may have various applications, such as home networking, smartposter, or bus ticketing.

An NFC-supported electronic device may communicate with otherNFC-supported electronic devices through at least one of, e.g., a readermode, a card emulation mode, and a peer-to-peer mode.

DISCLOSURE Technical Problem

An object of the present invention is to provide an electronic devicethat may effectively solve collisions that may occur upon handover forswitching an NFC link to an alternative communication link and a methodof operating the electronic device.

Objects of the present invention are not limited thereto, and otherobjects may be apparent to those skilled in the art from the descriptiontaken in conjunction with the accompanying drawings.

Technical Solution

According to a first aspect of the present invention, a method ofresolving a handover collision of a first electronic device includes thesteps of transmitting through a first communication link to a secondelectronic device a first handover request message to request formationof a second communication link that has a different type from the typeof the first communication link, receiving from the second electronicdevice through the first communication link a second handover requestmessage to request formation of a third communication link that has adifferent type from the type of the first communication link beforereceiving a first response message in response to the first handoverrequest message, and determining whether to transmit a second responsemessage to the second electronic device in response to the secondhandover request message.

According to a first aspect of the present invention, a first electronicdevice includes a controller, one or more alternative communicationmeans, and a communication unit, wherein the controller transmitsthrough a first communication link formed through the communication unitto a second electronic device a first handover request message torequest formation of a second communication link that has a differenttype from the type of the first communication link, and when receivingfrom the second electronic device through the first communication link asecond handover request message to request formation of a thirdcommunication link that has a different type from the type of the firstcommunication link before receiving a first response message in responseto the first handover request message, determines whether to transmit asecond response message to the second electronic device in response tothe second handover request message.

Advantageous Effects

The electronic device and the method of operating the same according tothe present invention may effectively resolve collisions that occurduring the course of handover.

DESCRIPTION OF DRAWINGS

FIG. 1 shows a system environment according to an embodiment of thepresent invention.

FIG. 2 is a view for describing the handover according to a firstembodiment of the present invention.

FIG. 3 is a view for describing a handover according to a secondembodiment of the present invention.

FIG. 4 is a view for describing a handover according to a thirdembodiment of the present invention.

FIG. 5 is a view for describing a handover according to a fourthembodiment of the present invention.

FIG. 6 is a view for describing a handover request collision accordingto an embodiment of the present invention.

FIG. 7 is a view for describing a method of resolving the handoverrequest collision according to a first embodiment of the presentinvention.

FIG. 8 illustrates a structure of a handover message according to anembodiment of the present invention.

FIG. 9 illustrates an example of a handover request message according toan embodiment of the present invention.

FIG. 10 illustrates an example of a handover selection message accordingto an embodiment of the present invention.

FIG. 11 illustrates an example of a handover request record according toan embodiment of the present invention.

FIG. 12 illustrates an example of a handover selection record accordingto an embodiment of the present invention.

FIG. 13 illustrates an example of a handover carrier record according toan embodiment of the present invention.

FIG. 14 illustrates an example of an alternative carrier recordaccording to an embodiment of the present invention.

FIG. 15 illustrates an example of a handover request message when thealternative carrier is Wi-Fi according to an embodiment of the presentinvention.

FIG. 16 illustrates a binary content of the Wi-Fi handover requestmessage according to an embodiment of the present invention.

FIG. 17 illustrates a handover selection message when the alternativecarrier is Wi-Fi according to an embodiment of the present invention.

FIG. 18 illustrates a binary content of a handover selection messageaccording to an embodiment of the present invention.

FIG. 19 illustrates an example of a handover request message when thealternative carrier is Bluetooth according to an embodiment of thepresent invention.

FIG. 20 illustrates a binary content of a Bluetooth handover requestmessage according to an embodiment of the present invention.

FIG. 21 illustrates an example of a handover selection message when thealternative carrier is Bluetooth according to an embodiment of thepresent invention.

FIG. 22 illustrates a binary content of a Bluetooth handover requestmessage according to an embodiment of the present invention.

FIG. 23 illustrates an example of a handover request message usingadditional data according to a first embodiment of the presentinvention.

FIG. 24 is a view for describing an example of a handover selectionmessage using additional data according to a first embodiment of thepresent invention.

FIG. 25 illustrates a handover request message utilizing additional dataaccording to a second embodiment of the present invention.

FIG. 26 illustrates additional data of a handover selection messageutilizing additional data according to a second embodiment of thepresent invention.

BEST MODE

The above and other objects, features, and advantages will be moreapparent from the detailed description taken in conjunction with theaccompanying drawings. Embodiments of the present invention will bedescribed with reference to the accompanying drawings. Throughout thespecification, the same reference numerals may be used to denote thesame or substantially the same elements. The detailed description onknown functions or configurations associated with the invention will beomitted when determined to render the gist of the inventionunnecessarily unclear.

FIG. 1 shows a system environment according to an embodiment of thepresent invention.

The system environment may include one or more NFC electronic devicesthat may form an NFC link.

Referring to FIG. 1, the system environment may include one or moreelectronic devices 100, 200, and 300. This configuration is notnecessary and thus more or less components may be included. As usedherein, the electronic devices 100, 200 and 300 refer to any electronicdevices that support NFC communication, such as, for example,NFC-supported mobile data processing devices (e.g., cell phones,smartphones, or e-book readers), printers, TVs, DTVs, computers,tablets, audio devices, or any other electronic devices. These aremerely examples of the electronic devices and further various types ofelectronic devices may be included. Hereinafter, the electronic devicesmay be referred to as “NFC electronic devices”.

As shown in FIG. 1, the electronic device 100 may include a host 110, anNFC communication module 120, and one or more alternative communicationcarriers.

The host 110 may provide a function of a process that controls thecomponents of the electronic device 100. For example, the host 110 mayreceive and/or output various signals for controlling one or morealternative communication carriers and the NFC communication module 120shown in FIG. 1. Hereinafter, the host 110 may be referred to as aprocessor 110 or a controller.

The NFC communication module 120 may allow the electronic device 100 toform an NFC link with the other electronic devices 200 and 300 thatsupport NFC communication. The NFC communication module 120 may refer toan NFC forum device. As used herein, the NFC communication module may bereferred to as a near field communication means.

As shown in FIG. 1, the NFC communication module 120 may form an NFClink by performing tagging with the NFC communication modules of theother electronic devices within an NFC communication range.

The NFC communication module 120 may communicate with the NFCcommunication modules of the other electronic devices 200 and 300 invarious modes, such as, for example, a card emulation mode, a readermode, a peer-to-peer mode.

When operating in the card emulation mode, the NFC communication module120 of the electronic device 100 may function as a card, that is, a tag.In such case, the NFC communication modules of the other electronicdevices may operate in the reader mode to obtain data from the NFCcommunication module 120 of the electronic device 100.

When operating in the reader mode, the NFC communication module 120 ofthe electronic device 100 may function as a reader. In this case, theNFC communication module 120 of the electronic device 100 may obtaindata from the NFC communication modules of the other electronic devices.

When operating in the peer-to-peer mode, the NFC communication module120 of the electronic device 100 may exchange data with the NFCcommunication modules of the other electronic devices.

The mode of the NFC communication module 120 may be determined accordingto a predetermined criterion. For example, the mode of the NFCcommunication module 120 may be set according to a user's entry or apredetermined algorithm.

The alternative communication carrier refers to a communicationtechnology that may be used for data transmission between electronicdevices. The alternative communication carrier may include variouscommunication modules other than the NFC communication carrier. Forexample, as shown in FIG. 1, the alternative communication carrier mayinclude at least one of a Bluetooth (802.15.1 IEEE) communication module132 and a Wi-Fi (Wireless Fidelity) communication module 134. Besides,the alternative communication carrier may include various communicationmeans such as an RFID (Radio Frequency Identification) communicationmodule or a WiGig (Wireless Gigabit) communication module. Anycommunication means currently implemented or to be implemented in thefuture may also be included in the alternative communication carrier.Hereinafter, the alternative communication carrier may be referred to asan alternative carrier or an alternative communication means.

Although not shown, the electronic devices 200 and 300 may each includea configuration corresponding to the electronic device 100. That is, theelectronic devices 200 and 300 each may include a host, an NFCcommunication module, and an alternative communication carrier.

For convenience of description, as necessary, the electronic device 100is referred to as a first electronic device 100, the electronic device200 as a second electronic device 200, and the electronic device 300 asa third electronic device.

After forming the NFC link with the other electronic devices through theNFC communication module 120, the electronic device 100 forms anothertype of communication link different from the NFC link to continue toperform data communication with the other electronic devices. As usedherein, a series of procedures of allowing the electronic device 100 tobe linked to the other electronic devices through the alternativecommunication carrier so that the electronic device 100 may keepcommunicating with the other electronic devices through the alternativecommunication carrier after the NFC link is formed are referred to as“handover”.

In other words, the handover is to form an NFC link between theelectronic device 100 and the other electronic devices and then form alink through the alternative communication carrier to perform datacommunication. A user may easily form an NFC link through NFC taggingbetween the electronic device 100 and the other electronic device, thenchanging communication means through the alternative communicationcarrier appropriate for transmission of a high capacity of data and/ordata transmission in a longer distance than that of the NFC link.

Hereinafter, referring to the drawings, the handover according to anembodiment will be described in more detail. For convenience ofdescription, the system environment shown in FIG. 1 is referred to.However, this is merely for ease of description, and the technicalspirit of the invention is not limited to a particular environment orspecific machine.

FIG. 2 is a view for describing the handover according to a firstembodiment of the present invention.

Referring to FIG. 2, the first electronic device 100 may transmit ahandover request message to the second electronic device 200 (S110).

Prior to step S110, the first electronic device 100 and the secondelectronic device 200 may form a communication link through a firstcommunication means. For instance, the first electronic device 100 mayform an NFC link with the second electronic device 200 through tagging.

The first electronic device 100 may transfer a message for requestinghandover, e.g., the handover request message, to the second electronicdevice 200 through the NFC link thusly formed.

The first electronic device 100 may transmit the handover requestmessage to the second electronic device 200, and the second electronicdevice 200 may initiate a protocol for forming another communicationlink through the NFC link formed between the first electronic device 100and the second electronic device 200.

Specific information included in the handover request message will bedescribed later.

Here, the first electronic device 100 may serve as a handover requester,and the second electronic device 200 may serve as a handover selector.The handover requester refers to a device that starts a handoverprotocol by transmitting the handover request message to another NFCelectronic device, and the handover selector refers to an NFC devicethat configures a handover selection message and responds to thehandover request message. That is, the handover requester (i.e., adevice of requesting a handover) and the handover selector (i.e., adevice of selecting a handover) are relative concepts that are defineddepending on whether to transmit a handover request message or handoverselection message. Accordingly, depending on the situation, when thesecond electronic device 200 transmits a handover request message to thefirst electronic device 100, the first electronic device 100 becomes thehandover selector, and the second electronic device 200 becomes thehandover requestor.

The handover request message may include information associated with analternative carrier supported by the first electronic device 100. Forexample, as shown in FIG. 1, since the first electronic device 100supports Bluetooth and Wi-Fi, the handover request message may includeinformation on Bluetooth and Wi-Fi supported by the first electronicdevice 100. A specific data format included in the handover requestmessage will be described later.

Priorities may be assigned to a plurality of alternative carriers. Forexample, as shown in FIG. 2, the handover request message putsinformation on an alternative carrier having a higher priority at thefront and information on an alternative carrier having a lower priorityat the rear. Referring to the handover request message illustrated inFIG. 2, it can be seen that Wi-Fi, an alternative carrier, has a higherpriority than Bluetooth. Or, there may be a separate field in which apriority of each carrier is filled.

Receiving the handover request message, the second electronic device 200may transmit a response to the handover request message to the firstelectronic device 100 (S120).

For example, the second electronic device 200 may generate a handoverselection message as an example of a response to the handover requestmessage through the NFC link and may transmit the generated handoverselection message to the first electronic device 100.

The second electronic device 200 may determine which alternative carrieris supported by the second electronic device 200 among the alternativecarriers included in the handover request message and depending on thedetermination may provide information on the alternative carriersupported by the second electronic device 200 to the first electronicdevice 100. That is, the alternative carrier included in the handoverselection message may include information on the alternative carriersupported by the second electronic device 200 among the alternativecarriers supported by the first electronic device 100.

As shown in FIG. 2, the second electronic device 200 supports Bluetoothas an alternative carrier, but not Wi-Fi.

In such case, the handover selection message may include information ona Bluetooth communication module supported by the second electronicdevice 200 as information on the alternative carrier.

Specific information included in the handover selection message will bedescribed later.

The first electronic device 100 may perform data communication with thesecond electronic device 200 through the alternative carrier (S130).

For this, the first electronic device 100 may obtain information on thealternative carrier supported by the second electronic device 200 byreceiving the handover selection message from the second electronicdevice 200. For example, the first electronic device 100 may identifythat the alternative carrier supported by the second electronic device200 as obtained is Bluetooth.

Accordingly, based on the information obtained by transmission andreception of the handover request message and the handover selectionmessage, the first electronic device 100 may perform a series ofprocedures for handover to a carrier other than the second electronicdevice 200. For example, to change the NFC link to a Bluetooth link,Bluetooth pairing may be carried out between the first electronic device100 and the second electronic device 200. By doing so, the firstelectronic device 100 and the second electronic device 200 may switchfrom the NFC link to the Bluetooth link and may continue to performcommunication based on the Bluetooth protocol.

As the link between the first electronic device 100 and the secondelectronic device 200 switches from the NFC link to the Bluetooth link,although not positioned in the NFC communication range any longer, thefirst electronic device 100 and the second electronic device 200 maystill perform data communication and exchange data at a higher speedthan that of the NFC link.

In other words, in the case that the first electronic device 100 is asmartphone, a user may place his smartphone near the second electronicdevice 200 so that the smartphone may conduct tagging with the secondelectronic device 200, thus forming an NFC link and performing thehandover protocol to thereby change the link means to Bluetooth. Sincethe link means is changed, even when the user brings his smartphone outof the NFC communication range, the smartphone may continue to performdata communication with the second electronic device 200 throughBluetooth.

The handover process described in connection with steps S110 to S130 arehereinafter referred to as “negotiated handover”. That is, thenegotiated handover refers to exchange of messages for agreement on thealternative carrier used for data exchange between two first NFCelectronic devices 100, e.g., the electronic devices 100 and 200. Asused herein, the handover may refer to the negotiated handover.

Hereinafter, another embodiment of the above-described negotiatedhandover will be described.

FIG. 3 is a view for describing a handover according to a secondembodiment of the present invention.

In describing the handover according to the second embodiment, what issubstantially the same as the first embodiment will not be repeatedlydescribed.

Referring to FIG. 3, the third electronic device 300, unlike the secondelectronic device 200 shown in FIG. 2, may simultaneously support aplurality of alternative carriers, for example, Bluetooth and Wi-Fi.

The first electronic device 100 may transmit a handover request messageto the third electronic device 300 (S210). In other words, the firstelectronic device 100 becomes a handover requester, and the thirdelectronic device 300 becomes a handover selector. Step S210 is the sameas step S110 described in connection with FIG. 2, and the descriptionwill be omitted.

The third electronic device 300 may transmit a handover selectionmessage to the first electronic device 100 in response to the handoverrequest message (S220).

The handover selection message transmitted by the third electronicdevice 300 may include information on Wi-Fi and Bluetooth which arealternative carriers. Also, the handover selection message, as shown inFIG. 3, places Wi-Fi before Bluetooth, thereby assigning a higherpriority to Wi-Fi.

The first electronic device 100 may communicate with the thirdelectronic device 300 through the alternative carrier (S230).

The first electronic device 100 may judge that the third electronicdevice 300 supports a plurality of alternative carriers based on thehandover selection message obtained in step S120.

When the handover selector, i.e., the third electronic device 300,supports the plurality of alternative carriers, the first electronicdevice 100 may select one or all of the plurality of alternativecarriers. Further, when selecting one of the alternative carriers, thefirst electronic device 100 may make the selection depending on thepriorities of the alternative carriers designated by the thirdelectronic device 300 or may select its preferred one irrespective ofsuch priorities.

Referring to FIG. 3, the first electronic device 100 may selectBluetooth as the alternative carrier regardless of the prioritiesassigned to the alternative carriers by the third electronic device 300.

FIG. 4 is a view for describing a handover according to a thirdembodiment of the present invention.

Step S310 of FIG. 4 is the same as step S210 of FIG. 3 and thus thedetailed description will be omitted.

The third electronic device 300 may transmit a handover selectionmessage to the first electronic device 100 (S330). At this time, asshown in FIG. 4, the handover selection message may assign a higherpriority to Bluetooth than Wi-Fi.

In such case, the first electronic device 100 may first attemptBluetooth pairing depending on the priorities designated by the thirdelectronic device 300 which is a handover selector among a plurality ofalternative carriers (S330).

The Bluetooth pairing may fail due to various causes. For example, whilethe handover protocol is in progress, if the first electronic device 100and the third electronic device 300 are positioned out of a range ofBluetooth signals, the Bluetooth pairing may not succeed.

Meanwhile, while the handover protocol goes on, if the first electronicdevice 100 and the third electronic device 300 are positioned within therange of Bluetooth signals so that handover to Bluetooth occurs andwhile data exchange is conducted through the Bluetooth link, at leastone of the first electronic device 100 and the third electronic device300 is on the move so that the devices 100 and 300 end up departing fromthe Bluetooth signal range, the Bluetooth link may fail.

At this time, the first electronic device 100 may continue to performdata communication with the third electronic device 300 through Wi-Fiwhich is an alternative carrier with the next priority (S340).

FIG. 5 is a view for describing a handover according to a fourthembodiment of the present invention.

Step S410 of FIG. 5 is the same as step S310 of FIG. 4 and thus thedetailed description will be omitted.

Referring to FIG. 5, the third electronic device 300 may transmit ahandover selection message to the first electronic device 100 inresponse to a handover request message received from the firstelectronic device 100 (S420).

The handover selection message may include power condition informationof alternative carriers provided by the third electronic device 300.

For example, if among alternative carriers supported by the firstelectronic device 100 are the alternative carrier supported by the thirdelectronic device 300, then a power condition of each of the alternativecarriers supported by the third electronic device 300—for example,information on activation or inactivation—may be transmitted from thethird electronic device 300 to the first electronic device 100.

For example, as shown in FIG. 5, the handover selection message mayinclude information indicating that Bluetooth and Wi-Fi, which arealternative carriers of the first electronic device 100, remaininactivated.

When the received handover selection message includes information on theplurality of alternative carriers, the first electronic device 100 mayselect any alternative carrier as described above. In this embodiment,it is assumed that the first electronic device 100 selects Wi-Fi as thealternative carrier.

The first electronic device 100 re-transmits the handover requestmessage to the third electronic device 300 (S430). The handover requestmessage transmitted in step S430 may designate one of the receivedplurality of alternative carriers. That is, the first electronic device100 may designate Wi-Fi as the alternative carrier in step S430 and maytransmit to the third electronic device 300 a handover request messagedesignating Wi-Fi only as the alternative carrier, so that the Wi-Fimodule of the third electronic device 300 may be activated.

In response to the handover request message received in step S430, thethird electronic device 300 may activate power of the Wi-Fi module andmay transmit a message responding to the handover request messagereceived in step S430 to the first electronic device 100 (S440).

The first electronic device 100 may perform data exchange with the firstelectronic device 100 through Wi-Fi (S450).

In other words, when the Wi-Fi module of the third electronic device 300is activated, the first electronic device 100 may form a Wi-Fi link withthe third electronic device 300. That is, the first electronic device100 may hand the NFC link with the third electronic device 300 over tothe Wi-Fi link.

According to the embodiment described in connection with FIG. 5, thethird electronic device 300, which is a handover selector, leaves thepower of the alternative carrier inactivated until a specificalternative carrier is selected from the plurality of alternativecarriers, thereby saving power.

A variety of handover processes have been so far described according toseveral embodiments. Hereinafter, a handover request collision that mayoccur during the course of handover and a solution thereto will bedescribed in greater detail.

FIG. 6 is a view for describing a handover request collision accordingto an embodiment of the present invention.

As used herein, the “handover request collision” refers to a situationwhere after an NFC link is formed between the first electronic device100 and the second electronic device 200, the first electronic device100 transmits a handover request message to the second electronic device200, and the second electronic device 200 transmits a handover requestmessage to the first electronic device 100—that is, both the firstelectronic device 100 and the second electronic device 200 send outrespective handover request messages. In the embodiment described inconnection with FIGS. 2 to 5, an electronic device functions as ahandover requester, and its counterpart electronic device functions as ahandover selector. However, when the handover request collision takesplace, both the electronic devices function as the handover requesters.

Specifically, referring to FIG. 6, while an NFC link is formed betweenthe first electronic device 100 and the second electronic device 200,the first electronic device 100 transmits a first handover requestmessage HRa to the second electronic device 200 (S510).

The second electronic device 200 also transmits a second handoverrequest message HRb to the first electronic device 100 (S520).

Based on the description made in connection with FIGS. 2 to 3, receivingthe first handover request message HRa, the second electronic device 200should transmit a handover selection message to the first electronicdevice 100 in response to the first handover request message HRa.However, since the second electronic device 200 transmits the secondhandover request message HRb to the first electronic device 100, ahandover request collision occurs between the first electronic device100 and the second electronic device 200 that both serve as the handoverrequest devices.

In such case, one of the first electronic device 100 and the secondelectronic device 200 should be a handover selector. It is hereinafterreferred to as “handover collision resolution” to determine which one ofthe first electronic device 100 and the second electronic device 200 isto be the handover selector.

The first electronic device 100 and the second electronic device 200performs a handover collision resolution process (S530), which will bedescribed below in more detail.

On the other hand, when receiving a handover request message fromanother electronic device before sending its own handover requestmessage to the other electronic device, the first electronic device 100processes the handover request message received from the otherelectronic device without sending its own handover request message tothe other electronic device—that is, the first electronic device 100plays a role as a handover selector—thereby achieving the handoverprocess.

Hereinafter, the handover collision resolution performed by the firstelectronic device 100 and the second electronic device 200 in step S530will be more specifically described. The handover collision resolutionmay be conducted by various methods. This will be described in detailwith reference to the drawings.

FIG. 7 is a view for describing a method of resolving the handoverrequest collision according to a first embodiment of the presentinvention. In describing steps S610 and S620 of FIG. 7, what are thesame as those described in connection with steps S510 and S520 will notbe repeatedly described. Also, for ease of description, it is assumedthat there is a handover request collision between the first electronicdevice 100 and the second electronic device 200. However, this is merelyan example, and the technical spirit of the invention is not limited toa specific device.

The first electronic device 100 and the second electronic device 200perform a handover request collision resolution (S630). That is, thefirst electronic device 100 and the second electronic device 200 mayeach perform the handover request collision resolution. Hereinafter, forconvenience of description, the handover request collision solution bythe first electronic device 100 is described, but the handover requestcollision resolution process may be also performed by the secondelectronic device 200 in the same manner.

The first electronic device 100 may compare a specific field valueincluded in the first handover request message HRa transmitted with aspecific field value included in the second handover request message HRbreceived.

For example, the specific field value may include a random number.

Specifically, when transmitting the first handover request message HRato the second electronic device 200 in step S610, the first electronicdevice 100 generates the random number, includes the random number inthe specific field value of the first handover request message HRa, andtransmits the first handover request message HRa.

Upon transmitting the second handover request message HRb to the firstelectronic device 100 in step S620, the second electronic device 200 mayalso generate a random number and transmit the second handover requestmessage HRb with the random number included in the specific field valueof the second handover request message HRb.

By doing so, each of the first electronic device 100 and the secondelectronic device 200 may obtain the random numbers included in thehandover request message received from its counterpart device and thehandover request message transmitted to its counterpart device and maycompare the random numbers with each other.

The first electronic device 100 may determine whether to function as ahandover requester or handover selector by comparing the random numberincluded in the first handover request message HRa transmitted to thesecond electronic device 200 with the random number included in thesecond handover request message HRb received from the second electronicdevice 200.

Depending on whether the two random numbers are identical to ordifferent from each other, the first electronic device 100 may performthe following steps.

For example, when the two random numbers are the same as each other, thefirst electronic device 100 may re-transmit the handover request messageto the second electronic device 200. The first electronic device 100re-generate a random number and transmits the re-generated random numberto the second electronic device 200 with the re-generated random numberincluded in the specific field of the handover request message.

When the two random numbers are different from each other, theelectronic device that has transmitted a handover request message havinga higher priority may serve as the handover requester.

More specifically, to determine the priority, the first electronicdevice 100 may consider one or more bit values included in thetransmitted first handover request message HRa and the received secondhandover request message HRb. For example, the one or more bit valuesmay be bit values included at the same position in the random number.

That is, the first electronic device 100 may determine whether tofunction as the handover requester or handover selector depending on aresult of comparing a specific bit value of the random number with aspecific bit value of the received random number.

For example, the first electronic device 100 may determine based on thecomparison result of the specific bit values whether the specific bitvalue transmitted from the first electronic device 100 is identical toor different from the specific bit value received from the secondelectronic device 200 and may determine whether to serve as the handoverselector based on the result of the determination and the magnitudes ofthe transmitted random number and the received random number.

More specifically, for example, in the case that the comparison resultof the specific bit values shows that the specific bit values are thesame as each other, when the random number generated by the firstelectronic device 100 is larger than the random number generated by thesecond electronic device 200, the first electronic device 100 mayfunction as the handover selector. In such case, since the specific bitvalues are the same as each other and the second electronic device 200generates the random number smaller than that generated by the firstelectronic device 100, the second electronic device 200 may function asthe handover requester.

Meanwhile, in the case that the comparison result of the specific bitvalues shows that the specific bit values are different from each other,when the random number generated by the first electronic device 100 islarger than the random number generated by the second electronic device200, the first electronic device 100 may function as the handoverrequester. In such case, since the specific bit values are differentfrom each other and the second electronic device 200 generates therandom number smaller than that generated by the first electronic device100, the second electronic device 200 may function as the handoverselector.

That is, it may be determined which device is the handover requester orhandover selector in consideration of both the comparison result of thespecific bit values and the magnitudes of the random numbers, so that adevice generating a larger/smaller random number may be prevented frombeing unconditionally selected as the handover requester or handoverselector.

Hereinafter, it is assumed based on the handover request collisionresolution that the first electronic device 100 functions as thehandover requester, and the second electronic device 200 functions asthe handover selector.

In response to the first handover request message HRa received in stepS610, the second electronic device 200 may transmit a handover selectionmessage to the first electronic device 100 (S640).

On the other hand, since the first electronic device 100 has beenselected to function as the handover requester according to the handoverrequest collision resolution, the first electronic device 100 does notrespond to the second handover request message HRb received from thesecond electronic device 200 in step S620.

According to the handover selection message received from the secondelectronic device 200 in step S640, the first electronic device 100 maycomplete the handover process (S650). In other words, by performing thesame process as the handover process described in connection with FIGS.2 to 5, the first electronic device 100 may complete the handoverprocess. Thus, the first electronic device 100 and the second electronicdevice 200 may exchange data through the alternative communicationmeans.

Therefore, according to the embodiment described in connection withFIGS. 6 and 7, the collision that may occur during the course of thehandover process may be effectively resolved.

Hereinafter, a data structure according to an embodiment of the presentinvention will be described in detail with reference to the drawings.The data structure is merely an example, and the technical spirit of theinvention is not limited to a specific data structure.

FIG. 8 illustrates a structure of a handover message according to anembodiment of the present invention. As illustrated earlier in FIGS. 2to 7, the message used in the handover process may include a handoverrequest message and a handover selection message.

Referring to the upper part of FIG. 8, the handover request messageaccording to an embodiment of the present invention may include ahandover request record (hereinafter, “Hr record”) and one or more NDEF(NFC Data Exchange Format) records. Also, the handover selection message(hereinafter, “Hs record”) may include a handover selection record andone or more NDEF records.

The NDEF records may include specific information on the alternativecarrier.

Specifically, various types of information may be included in the NDEFrecords of the handover request message.

For example, the NDEF records may include information for identifying analternative communication link. That is, the handover carrier record mayprovide the handover selector with information on what alternativecommunication means is supported by the handover requester. As usedherein, the NDEF record including the information for identifying analternative communication link is referred to as a “handover carrierrecord”.

Meanwhile, the NDEF records may include environment setup informationfor forming an alternative communication link. As used herein, the NDEFrecord including environment setup information necessary for forming analternative communication link, such as a password or an address, isreferred to as a “carrier environment setup record”.

The carrier environment setup record may also include information foridentifying what the alternative communication means is.

The handover carrier record and the carrier environment setup recordwill be described later in greater detail.

Referring to the middle part of FIG. 8, the handover request/selectionrecord according to an embodiment of the present invention may includeat least one of a header Hdr, a version field, and one or morealternative carrier records (hereinafter, “ac record”), and thealternative carrier records may define an alternative carrierrequested/selected by the handover request/selection message. Further,the handover request/selection record may include more or lessinformation fields that those illustrated therein.

Referring to the lower part of FIG. 8, the ac record according to anembodiment of the present invention may include at least one of a headerHdr, a carrier power state, a carrier data reference, an auxiliary datareference count, and information fields of one or more auxiliary datareferences.

The carrier data reference and the auxiliary data references mayindicate their corresponding NDEF records as illustrated in the upperpart of FIG. 8.

Hereinafter, the above-referenced information will be described ingreater detail.

FIG. 9 illustrates an example of a handover request message according toan embodiment of the present invention.

As described in connection with FIGS. 2 to 7, the handover requestmessage may be used for the handover requester to provide the handoverselector with information for an alternative carrier supported by thehandover requester.

The handover request message may include the handover request record andone or more NDEF records. For example, the handover request message maystart with the handover request record and terminate with the NDEFrecord.

Specifically, the handover request message may start with the handoverrequest record including a flag set as a message beginning MB and mayterminate with the NDEF record with a flag set as a message end ME.

Since the handover request message should include at least onealternative carrier, it cannot have a record with both the MB and MEflags set.

The NDEF record may be one of the handover carrier record and thecarrier environment setup record depending on characteristics of thealternative carrier. Also, the NDEF record may be configured asauxiliary data. The NDEF record will be described later morespecifically.

FIG. 10 illustrates an example of a handover selection message accordingto an embodiment of the present invention.

As described in connection with FIGS. 2 to 7, the handover selectionmessage may be used for the handover selector to provide the handoverrequester with information for an alternative carrier supported by thehandover selector among alternative carriers included in the handoverrequest message received from the handover requester.

Referring to the upper part of FIG. 10, the handover selection messagemay have the same structure as that of the handover request messagedescribed in connection with FIG. 9.

Further, referring to the lower part of FIG. 10, the handover selectionmessage may include a single record with both a message beginning MB anda message end ME set. That is, in such case, none of the alternativecarriers supported by the handover requester are supported by thehandover selector.

Hereinafter, the handover request record illustrated in FIGS. 8 and 9will be described in greater detail.

FIG. 11 illustrates an example of a handover request record according toan embodiment of the present invention.

The handover request record may include a list of alternative carriersthat may be used by the handover requester for communication with thehandover selector.

The handover request record may indicate at least one or morealternative records.

Referring to FIG. 11, the handover request record may includeinformation on at least one of major version, minor version, collisionresolution record, and alternative carrier records 1 to n.

The collision resolution record may include random numbers for resolvingthe handover request collision as described in connection with FIG. 7.

Each alternative carrier record may specify an alternative carriersupported by the handover requester for communication between thehandover selector and the handover requester. Information on thealternative carrier specified by each alternative carrier record may beincluded in the NDEF record of the handover request message.

Hereinafter, the handover selection record illustrated in FIGS. 8 and 10will be described in greater detail.

FIG. 12 illustrates an example of a handover selection record accordingto an embodiment of the present invention.

The handover selection record may include information on the alternativecarrier supported by the handover selector among the alternativecarriers included in the handover request message received from thehandover requester by the handover selector.

As shown in FIG. 12, the handover selection record may includeinformation on at least one of major version, minor version, andalternative carrier records 1 to n.

The alternative carrier records of the handover selection record mayinclude information on the alternative carrier supported by both thehandover requester and the handover selector.

Also, the order of the alternative carriers included in the handoverselection record may refer to the order of priorities of the alternativecarriers preferred by the handover selector. For example, thealternative carrier indicated by the alternative carrier record 1 mayhave a higher priority than that of the alternative carrier indicated bythe alternative carrier record n. This may apply to the embodimentdescribed in connection with FIGS. 3 to 5.

Hereinafter, the handover carrier record, which is an example of theNDEF record illustrated in FIGS. 8 and 9, will be described in greaterdetail.

FIG. 13 illustrates an example of a handover carrier record according toan embodiment of the present invention.

The handover carrier record may include information for identifying analternative carrier.

Referring to FIG. 13, the handover carrier record may include at leastone of a carrier type format (hereinafter, “CTF”), a carrier typelength, a carrier type, and carrier data.

The carrier type format may indicate a structure of a value written inthe carrier type to be described later.

For example, the carrier type format may correspond to at least one ofan NFC Forum well-known type, a media-type defined in RFC 2046, anabsolute URI defined in RFC 3986, and an NFC external type.

The carrier type length may refer to the length of the carrier type tobe described later.

The carrier type may provide a unique identifier for an alternativecarrier. The value of the carrier type should follow a structure,encoding, and format according to the carrier type format.

Based on at least one of the carrier type format, carrier type length,and carrier type—more specifically, the carrier type, the handoverselector may identify what alternative carrier is supported by thehandover requester.

The carrier data may include additional information on the alternativecarrier.

Meanwhile, the handover carrier record may be included in the handoverrequest message as the NDEF record of the handover request message.Receiving the handover carrier record, the handover selector maytransmit to the handover requester environment setup information for thealternative carrier identified by the handover carrier record, forexample, the handover selection message including the carrierenvironment setup record. Receiving the carrier environment setuprecord, the handover requester may perform handover according to theenvironment setup information included in the carrier environment setuprecord.

Hereinafter, the alternative carrier record (ac Record) illustrated inFIGS. 8 and 12 will be described in greater detail.

FIG. 14 illustrates an example of an alternative carrier recordaccording to an embodiment of the present invention.

The alternative carrier record may be included in the handover requestrecord or the handover selection record.

As shown in FIG. 14, the alternative carrier record may include at leastone of a carrier power state CPS, a carrier data referenceCARRIER_DATA_REFERENCE, an auxiliary data reference countAUXILIARY_DATA_REFERENCE_COUNT, and auxiliary data references 1 to nAUXILIARY_DATA_REFERENCE 1 TO N.

The carrier power state refers to the power state of the alternativecarrier. The carrier power state may be at least one of, e.g.,“inactivated”, “activated”, “under activation”, and “unknown”.

The carrier power state may apply to step S420 described in connectionwith FIG. 5.

The carrier data reference may provide a function of indicating the NDEFrecord illustrated in the upper part of FIG. 8. As described earlier,the NDEF record may be the handover carrier record or carrierenvironment setup record.

The auxiliary data reference count may refer to the number of auxiliarydata references that follow.

The auxiliary data reference may indicate the NDEF record that providesadditional information on the alternative carrier.

The message structure has been so far described. Hereinafter, an exampleof information included in the message structure will be describedaccording to the type of the alternative carrier.

FIG. 15 illustrates an example of a handover request message when thealternative carrier is Wi-Fi according to an embodiment of the presentinvention. As illustrated in FIG. 15, the handover request message mayinclude the handover request record and the handover carrier record.That is, as described above, when the handover requester designatesWi-Fi as the alternative carrier, the NDEF record may have a format ofthe handover carrier that may include information for identifying Wi-Fi.

FIG. 16 illustrates a binary content of the Wi-Fi handover requestmessage according to an embodiment of the present invention. That is,FIG. 16 illustrates another representation for the handover requestmessage shown in FIG. 15.

FIG. 17 illustrates a handover selection message when the alternativecarrier is Wi-Fi according to an embodiment of the present invention. Asshown in FIG. 17, the handover selection message may include thehandover selection record and the carrier environment setup record. Thatis, the carrier environment setup record is an example of the NDEFrecord described in connection with FIG. 8.

Referring to FIG. 17, the carrier environment setup record provided bythe handover selector may include environment setup informationnecessary for the handover requester to access the alternative carrierprovided by the handover selector, for example, information on serviceset identifier (SSID), authentication type TLV, encryption type TLV,network key, and MAC address TLV.

In other words, based on the information included in the handovercarrier record received from the handover requester, the handoverselector identifies that the alternative carrier supported by thehandover requester is Wi-Fi, when the handover selector supports Wi-Fi,generates environment setup information necessary for the handoverrequester to form a Wi-Fi link with the handover selector, and transmitsthe generated environment setup information with the environment setupinformation included in the carrier environment setup record.

The handover requester may access the alternative carrier provided bythe handover selector, for example, Wi-Fi, based on the carrierenvironment setup information received from the handover selector.

FIG. 18 illustrates a binary content of a handover selection messageaccording to an embodiment of the present invention. That is, FIG. 18shows another representation of the handover selection messageillustrated in FIG. 17.

Although the embodiment described in connection with FIGS. 15 to 18assumes that the alternative carrier is Wi-Fi, the embodiments may alsoapply to any type of alternative carriers in which the handoverrequester need not provide the alternative carrier environment setupinformation to the handover selector.

The handover request/selection messages that may be implemented when thealternative carrier is Wi-Fi have been described so far in connectionwith FIGS. 15 to 18. This may also apply to the embodiment described inconnection with FIGS. 2 to 7.

Hereinafter, information including the handover request/selectionmessages when the alternative carrier is Bluetooth will be describedwith reference to the drawings.

FIG. 19 illustrates an example of a handover request message when thealternative carrier is Bluetooth according to an embodiment of thepresent invention. Referring to FIG. 19, the handover request messagemay include the handover request record and the carrier environmentsetup record.

As shown in FIG. 19, the carrier environment setup record may includeenvironment setup information necessary for the handover selector toaccess the alternative carrier provided by the handover requester, forexample, Bluetooth. Meanwhile, even when the alternative communicationmeans is Bluetooth, if there is no security means for Bluetooth, thecarrier environment setup record of the handover request message may bereplaced with the handover carrier record.

The information illustrated in FIG. 19 is apparent to those skilled inthe art, and the detailed description is thus omitted.

FIG. 20 illustrates a binary content of a Bluetooth handover requestmessage according to an embodiment of the present invention. That is,FIG. 20 shows another representation of the handover request message ofFIG. 19.

FIG. 21 illustrates an example of a handover selection message when thealternative carrier is Bluetooth according to an embodiment of thepresent invention.

FIG. 21 illustrates an example of a handover selection message when thealternative carrier is Bluetooth according to an embodiment of thepresent invention. Referring to FIG. 21, the handover selection messagemay include the handover selection record and the carrier environmentsetup record.

As shown in FIG. 21, the carrier environment setup record may includeenvironment setup information necessary for the handover requester toaccess the alternative carrier provided by the handover selector, forexample, Bluetooth.

FIG. 22 illustrates a binary content of a Bluetooth handover requestmessage according to an embodiment of the present invention. That is,FIG. 22 illustrates another representation of the handover selectionmessage shown in FIG. 21.

Although the embodiments described in connection with FIGS. 19 to 22assume that the alternative carrier is Bluetooth, the technical spiritof the invention is not limited to a specific carrier.

Further, although the embodiments described in connection with FIGS. 15to 22 assume that one alternative carrier is provided, a plurality ofalternative carriers may also be provided as illustrated in FIGS. 2 to5. In such case, the handover request/selection messages shown in FIGS.15 to 22 may each include information on a plurality of alternativecarriers.

Hereinafter, a method of performing a handover will be described usingthe auxiliary data described in connection with FIG. 8.

FIG. 23 illustrates an example of a handover request message usingadditional data according to a first embodiment of the presentinvention. The handover requester and the handover selector may open anFTP (File Transfer Protocol) session using the auxiliary data at thesame time with handover. In this embodiment, the alternative carrier isassumed to be Wi-Fi.

Referring to FIG. 23, the handover request message may include ahandover request record, a URI (Uniform Resource Identifier) record, anda handover carrier record which is an example of the NDEF record.

Referring to the handover request record illustrated in FIG. 23, thecarrier data reference is 0, and the auxiliary data reference is 1. Thatis, the handover carrier record has payload ID 0, and the auxiliary datahas payload ID 1. In other words, the URI record whose payload ID is 1may belong to the auxiliary data.

The handover carrier record is the same as that described in connectionwith FIG. 15, and the detailed description is thus omitted.

The URI record which is the auxiliary data represents that the handoverrequester may perform the FTP. For example, the handover request messageincludes auxiliary data associated with the FTP so that it may be knownto the handover selector that the handover requester supports the FTP.

FIG. 24 is a view for describing an example of a handover selectionmessage using additional data according to a first embodiment of thepresent invention.

Referring to FIG. 24, the handover selection message may include ahandover selection record, a URI record, and a Wi-Fi carrier environmentsetup record which is an example of the NDEF record.

Referring to FIG. 24, the URI record which is auxiliary data may includea URI field value for opening an FTP session.

By doing so, the handover requester may open the FTP sessionsimultaneously with performing handover with the handover selector fromthe NFC link to Wi-Fi link.

Hereinafter, referring to FIGS. 25 and 26, there will be described amethod of obtaining information on devices connected to the handoverselector through an alternative carrier designated by the handoverrequester by the handover requester utilizing additional data togetherwith handover.

FIG. 25 illustrates a handover request message utilizing additional dataaccording to a second embodiment of the present invention. In thisembodiment, the alternative carrier is assumed to be Wi-Fi.

Referring to FIG. 25, the handover request message may include ahandover request record, an HTTP message record, and a handover carrierrecord which is an example of the NDEF record.

The handover request message shown in FIG. 25 allows for recognition ofa device linked through Wi-Fi to the handover selector while a requestof handover to Wi-Fi is simultaneously made to the handover selector.For example, the device connected through Wi-Fi to the handover selectormay include devices configuring a home network or an office network. Forexample, the home network or office network may be implemented by UPnP(Universal Plug & Play). The Wi-Fi network is merely an example, and anyother networks constituted of other alternative carriers may beincluded.

The HTTP message record illustrated in FIG. 25 includes a message, e.g.,M-search message, used for the devices in the UPnP network to recognizeeach other.

Further, the HTTP message record illustrated in FIG. 25 may include thetype of a device to be searched by the handover requester. For example,the HTTP message record may include information on the type of a Wi-Ficonnected device, for example, UPnP device. The type of the UPnP devicemay be designated by the ST (Search Target) illustrated in FIG. 25. Thetype of the UPnP device may include a variety of types, such asrenderer, server, printer, or scanner. The ST field may designate thetype of one or more UPnP devices to be searched, for example, a printerand a renderer, or may designate all types of the UPnP devices. When alltypes of UPnP devices are designated, the ST field may have a value ofssdp: all.

Hereinafter, the ST field of the HTTP message record is assumed todesignate all types of UPnP devices, i.e., ssdp: all.

FIG. 26 illustrates additional data of a handover selection messageutilizing additional data according to a second embodiment of thepresent invention.

FIG. 26 illustrates an example of additional data transmitted to thehandover requester in response to the handover request message receivedby the handover selector.

Referring to FIG. 26, the additional data transmitted from the handoverselector to the handover requester includes information on a Wi-Ficonnected UPnP device which is an alternative carrier. For example, theinformation on the UPnP device may include a USN (Unique Service Name)for identifying the service name and a device identifier. The deviceidentifier, as shown in FIG. 26, may be represented as UUID.

The handover requester performs handover to Wi-Fi while simultaneouslyobtaining information a Wi-Fi connected device, e.g., UPnP device,through the handover selector. By doing so, the handover selector mayrecognize the UPnP device which is part of the UPnP network in a moresimplified manner.

The various embodiments disclosed herein may be implemented alone or incombination thereof. Further, the steps constituting one of theembodiments may be implemented in combination with the stepsconstituting another of the embodiments. For example, the handoverprotocols described in connection with FIGS. 2 to 5 may be combined witheach other. Further, the handover collision resolution protocoldescribed herein may also apply to each of the handover protocolsdescribed in connection with FIGS. 2 to 5.

Although the exemplary embodiments of the present invention have beendescribed, it is understood that the present invention should not belimited to these exemplary embodiments but various changes andmodifications can be made by one ordinary skilled in the art within thespirit and scope of the present invention as hereinafter claimed.

INDUSTRIAL APPLICABILITY

According to the present invention, there may be provided an electronicdevice that may effectively resolve handover request collisions tothereby perform handover from an NFC link to an alternativecommunication link and a method of operating the electronic device.

What is claimed is:
 1. A method of establishing a communication linkbetween a first electronic device and a second electronic device, themethod comprising: transmitting to the second electronic device a firsthandover request message including plural alternative carrierinformation for respective plural alternative communication links;receiving a first handover select message including plural alternativecarrier information for the plural alternative communication links fromthe second electronic device in response to the first handover requestmessage; wherein the first handover request message includes collisionresolution information and each of the plural alternative carrierinformation of the first handover select message includes first powerstate information being set to an inactive state; transmitting a secondhandover request message including the carrier information for one ofthe plural alternative communication links to the second electronicdevice; receiving a second handover select message from the secondelectronic device transmitted in response to the second handover requestmessage; wherein the second handover select message includes secondpower state information of the one of the plural alternative carrierinformation of the one of the plural alternative communication links,the second power state information being set to an active state; andestablishing the communication link based on the one of the pluralalternative carrier information.
 2. The method of claim 1, wherein eachof the plural alternative carrier information includes at least one ofauxiliary data reference information and auxiliary data reference countinformation.
 3. The method of claim 1, wherein each of the firsthandover request message, the second handover request message, the firsthandover select message and the second handover select message includesversion information, and the version information indicates informationrelated to a backward compatibility.
 4. The method of claim 1, whereineach of the first handover request message, the second handover requestmessage, the first handover select message and the second handoverselect message includes a first flag related to a beginning of a messageand a second flag related to an end of the message.
 5. The method ofclaim 4, wherein the first flag is set to 1 when the first flagindicates the beginning, and the second flag is set to 1 when the secondflag indicates the end.
 6. The method of claim 1, wherein the collisionresolution information comprises a number.
 7. The method of claim 6,wherein the collision resolution information comprises a random number.8. The method of claim 1, wherein the handover request messages and thehandover select messages are NFC (Near Field Communication) messages. 9.The method of claim 8, wherein the plural alternative communicationlinks comprise Wi-Fi and Bluetooth communication links.
 10. Apparatus ina first electronic device for establishing a communication link betweenthe first electronic device and a second electronic device, theapparatus comprising: a transmitter configured to transmit to the secondelectronic device a first handover request message including pluralalternative carrier information for respective plural alternativecommunication links; a receiver configured to receive from the secondelectronic device a first handover select message including pluralalternative carrier information for the plural alternative communicationlinks in response to the first handover request message; wherein thefirst handover request message includes collision resolution informationand each of the plural alternative carrier information of the firsthandover select message includes first power state information being setto an inactive state; the transmitter configured to transmit to thesecond electronic device a second handover request message including thealternative carrier information for one of the plural alternativecommunication links; the receiver configured to receive from the secondelectronic device a second handover select message in response to thesecond handover request message; wherein the second handover selectmessage includes second power state information of the one of the pluralalternative carrier information for the one of the plural alternativecommunication links, the second power state information being set to anactive state; and a controller configured to establish the communicationlink based on the one of the plural alternative carrier information. 11.The electronic device of claim 10, wherein each of the pluralalternative carrier information includes at least one of auxiliary datareference information and auxiliary data reference count information.12. The electronic device of claim 10, wherein each of the firsthandover request message, the second handover request message, the firsthandover select message and the second handover select message includesversion information, and the version information indicates informationrelated to a backward compatibility.
 13. The electronic device of claim10, wherein each of the first handover request message, the secondhandover request message, the first handover select message and thesecond handover select message includes a first flag related to abeginning of a message and a second flag related to an end of themessage.
 14. The electronic device of claim 13, wherein the first flagis set to 1 when the first flag indicates the beginning, and the secondflag is set to 1 when the second flag indicates the end.
 15. Theapparatus of claim 10, wherein the collision resolution informationcomprises a number.
 16. The apparatus of claim 15, wherein the collisionresolution information comprises a random number.
 17. The apparatus ofclaim 16, wherein the handover request messages and the handover selectmessages are NFC (Near Field Communication) messages.
 18. The apparatusof claim 17, wherein the plural alternative communication links compriseWi-Fi and Bluetooth communication links.